Secondary condensate ports

Around here the new homes have several different methods of piping the secondary condensate drains.

The most noticeable difference is this:

Cheap house: secondary port is left plugged up with the factory plug.
(Pan and switch present also)

Mid to expensive house: secondary port is piped to the exterior over a window or to a pan with a float switch.

I always write up the plugged secondary port as an issue and state that the manuf. recommends it be used.

I looked yesterday in the installers manual for a new Rheem attic unit and found nothing about the condensate drains. It even had a checklist for the installer to use for determining proper installation and nothing there about the condensate lines. The portion of the unit that has the ports had a label that indicated ADP as the manuf. but no manual was there for it.

I have seen units with a clogged main with water ooozing out of the metal joints around the unit. Also remember the humidity that gets blown back into the house when the unit has excess water for prolonged periods.

Is there any code for this except for the catch all that requires the installer to follow the manuf’s specs? It’s hard to use that argument when the manuf’s document is not complete or unavailable on site.

Why always code? How about defending it with common sense? We are making recommendations to serve the best interest of our clients. :slight_smile:

I agree but tell that to the house flippers, builders and agents and they still refuse to fix it.

Some agents tell their client “it meets code so you can not ask the seller to change this”

You can take the time to explain issues like these to some people and they only act like they are listening. It could be that it is over their heads and they are embarrassed to ask questions. Builders are starting to refuse repairs around here because they will just sell the house to the next one in line. One large builder told me that only 10 percent of buyers get an inspection!!!

Its time for the state to require private home inspections and let the govt. employee inspectors just do the zoning, tree population and regulate the point of occupancy.

Also, on many of the newer units, the two ports are level with each other.
There is a baffle hidden inside the unit that determines which one is the primary and secondary. Without the documentation you can not tell if the primary drain is really the primary.

If it is backwards and the other is plugged you get excess humidity back into the house.

We have many builders around here, national and local so we see many different types of units, no way to keep up with all of the porting specifics.

When I hear a Realtor say that, I always tell my Clients that they can ask for anything they want to ask for and, if the Realtor is telling them that they can’t, perhaps the Realtor is not working in their best interest. That gets my Client’s attention.

Is this what you’re looking for, Bruce?

M1411.3.1 Auxiliary and secondary drain systems. In addition to the requirements of Section M1411.3, a secondary drain or auxiliary drain pan shall be required for each cooling or evaporator coil where damage to any building components will occur as a result of overflow from the equipment drain pan or stoppage in the condensate drain piping.

You are required to have a secondary drain, or float switch. You often see both, which is best. You are not required by code to have a secondary drain if a float switch is present. (I don’t have time to read manufacturer’s installation instructions for every unit.)

IRC M1411.3.1.3 “An auxiliary drain pan without a separate drain line shall be installed under the coils on which condensate will occur. This pan shall be equipped with a water level detection device conforming to UL 508 that will shut off the equipment served prior to overflow of the pan.”

Since the code leaves the installer a gray area…

Put another way for the sake of discussion:

When you do have a pan with a switch present:
How do you get the condensate to the pan?
I think the secondary port is required to be piped to the pan.
Many installers leave it plugged and think they have met code.

The code is written badly and actually is missing the detail for the secondary port/piping.

If I see a pan with a float switch present, its acceptable to me. Even if the 2nd port is plugged at the evaporator coil. The water will find a way out and into the pan. You may be correct, but I don’t focus on whether the port is plugged at the coil.

With the secondary plugged, the water level will rise and only seep out of metal joints that are fairly well sealed. The excess water gets blown around inside the airhandler and onto the coil where the humidity gets blown into the duct (mold) and into the house (condensation around windows/mold)

When a major problem is found later by a subcontractor they change their tune and say “didn’t you have this inspected?”

I suggest everyone report plugged secondaries, the port is there for a reason.

I may change my tune. Let’s see what others say about it.

There are other similar threads but everyone kept drifting towards code or pan/pipe vs pan/switch.

***** This one is about getting the water out of the cabinet and off the coil when the primary is clogged.

What you do with the water when it is out of the cabinet is where code and personal preference come into play.

Most of the furnaces I see are in the attics here, but about half of them have no cooling condenser. However, when there is a cooling system present, this is what I like to see (notwithstanding the lack of a trap on the main drain). But even when I find this, I’ll go as far as recommending that my Clients have a float switch installed. I’ve seen the results of water damage to the ceilings when everything gets clogged. And the wasps love to create their mud homes in the exterior openings of these drain lines. Also recommend regular homeowner and monitoring to ensure that those wasps don’t block the drain pipes during cooling season.


RR, regarding maintenance, pour bleach down the opening on the primary once a year to help keep the drain open.

I have heard of that, but with the size of these mud dauber nests, all I would have is a drain pipe full of bleach. And since chlorine is naturally a gas, it dissipates into the atmosphere quite quickly. Perhaps more often might do the trick, but I’ve found a power nozzle on the hose works quite effectively.

The cliff swallows like to start their homes around the drain pipes, as well, eventually having a whole colony of nests with the drain pipe nowhere to be seen.

Note that in California, it is illegal to disturb nesting cliff swallows, so if you see active nesting, wait until the little babies have flown the nest before destroying the nests. I did make such a recommendation to a Client up in Poway. He had a few billion active nests. He thought I was kidding. Unfortunately, his neighbor was an active bird watcher and turned him in. Granted, it’s only a $50 misdemeanor fine, but I can do a lot of marketing with $50. Or make Ms Margarita and Dr Cuervo quite happy.

I see an occasional older unit with the secondary plugged. I see very few float switches in attic installations, these are more common on vertical closet units that I have seen. Commonly I see what I consider correct, and you seem to as weel, in newer construction with the secondary stubbed with a short pipe to the pan.

I have also run into the arrangement where the secondary is plumbed directly to the pipe running to the soffit and a tee allows the pan to drain to the same pipe. In most of these it would rely on the water seeping out of the cabinet to get to the pan, if the pan ever came into play. What is your opinion of this arrangement?

Secondary port and pan sharing the same pipe to the exterior is a good method. I just learned from an hvac guy that the pan should be 3 inches larger than the cabinet on all 4 sides to ensure that any condensation goes into the pan.